Improve Android configury

* configure.ac (JAVA_PUSH_LINT): New macro.
(JAVAFLAGS): New variable.  Check for various lint flags and
macros and enable them.
* java/Makefile.in (ANDROID_ABI):
* java/org/gnu/emacs/EmacsSdk7FontDriver.java: Remove compiler
warning.

java/org/gnu/emacs/EmacsSdk7FontDriver.java

@@ -325,7 +325,7 @@ public class EmacsSdk7FontDriver extends EmacsFontDriver
 	  list.add (new Sdk7FontEntity (typefaceList[i]));
       }
 
-    return (FontEntity[]) list.toArray (new FontEntity[0]);
+    return list.toArray (new FontEntity[0]);
   }
 
   @Override